1. Medical Technology Department, Faculty of Science, Islamic University-Gaza
MICROBIOLOGY
Dr. Abdelraouf A. Elmanama
Ph. D Microbiology
2008
Chapter 24
Microbial Diseases of the Respiratory System
2. 2008
Microbial Diseases of the Upper
Respiratory System
• Laryngitis: S. pneumoniae, S. pyogenes, viruses
• Tonsillitis: S. pneumoniae, S. pyogenes, viruses
• Sinusitis: Bacteria
• Epiglottitis: H. influenzae
3. 2008
• Upper respiratory normal microbiota may include
pathogens
Upper Respiratory System
Figure 24.1
4. 2008
Streptococcal pharyngitis (Strep throat)
Figure 24.3
• Streptococcus
pyogenes
• Resistant to
phagocytosis
• Streptokinases lyse
clots
• Streptolysins are
cytotoxic
• Diagnosis by indirect
agglutination
6. 2008
• Corynebacterium diphtheriae: Gram-positive rod
• Diphtheria membrane of fibrin, dead tissue, and
bacteria
• Diphtheria toxin produced by lysogenized C.
diphtheriae
• Prevented by DTaP and Td vaccine (Diphtheria toxoid)
• Cutaneous diphtheria: Infected skin wound leads to
slow healing ulcer
Diphtheria
8. 2008
Otitis Media
• S. pneumoniae (35%)
• H. influenzae (20-30%)
• M. catarrhalis (10-15%)
• S. pyogenes (8-10%)
• S. aureus (1-2%)
• Treated with broad-spectrum antibiotics
• Incidence of S. pneumoniae reduced by vaccine
15. 2008
Tuberculosis
Figure 24.9
• Mycobacterium
tuberculosis: Acid-fast
rod. Transmitted from
human to human
• M. bovis: <1% U.S.
cases, not transmitted
from human to human
• M. avium-intracellulare
complex infects people
with late stage HIV
infection
19. 2008
• Treatment of Tuberculosis: Prolonged treatment with
multiple antibiotics
• Vaccines: BCG, live, avirulent M. bovis. Not widely
used in U.S.
Tuberculosis
20. 2008
Tuberculosis
Figure 24.11
• Diagnosis: Tuberculin skin test screening
• + = current or previous infection
• Followed by X-ray or CT, acid-fast staining of
sputum, culturing bacteria
26. 2008
Mycoplasmal Pneumonia
Figure 24.14
• Mycoplasma
pneumoniae:
pleomorphic, wall-
less bacteria
• Also called primary
atypical pneumonia
and walking
pneumonia
• Common in children
and young adults
• Diagnosis by PCR or
by IgM antibodies
28. 2008
• Legionella pneumophila: Gram-negative rod
• L. pneumophila is found in water
• Transmitted by inhaling aerosols, not transmitted from
human to human
• Diagnosis: culturing bacteria
• Treatment: Erythromycin
Legionellosis
29. 2008
• Chlamydia psittaci: gram-negative intracellular
bacterium
• Transmitted by elementary bodies from bird dropping
to humans
• Reorganizes into reticulate body after being
phagocytized
• Diagnosis: culturing bacteria in eggs or cell culture
• Treatment: Tetracycline
Psittacosis (Ornithosis)
30. 2008
• Chlamydia pneumoniae
• Transmitted from human to human
• Diagnosis by FA test
• Treatment: Tetracycline
Chlamydial Pneumonia
31. 2008
Q fever
• Mycoplasma pneumoniae: pleomorphic, wall-less
bacteria
• Also called primary atypical pneumonia and walking
pneumonia
• Common in children and young adults
• Diagnosis by PCR or by IgM antibodies
33. 2008
• Viral pneumonia as a complication of influenza,
measles, chickenpox
• Viral etiology suspected if no cause determined
• Respiratory Syncytial Virus (RSV)
• Common in infants; 4500 deaths annually
• Causes cell fusion (syncytium) in cell culture
• Symptoms: coughing
• Diagnosis by serologic test for viruses and
antibodies
• Treatment: Ribavirin
Viral Pneumonia
34. 2008
• Chills, fever, headache, muscle aches (no intestinal
symptoms)
• 1% mortality due to secondary bacterial infections
• Treatment: Amantadine
• Vaccine for high-risk individuals
Influenza
35. 2008
• Hemagglutinin (H) spikes used for attachment to host
cells
• Neuraminidase (N) spikes used to release virus from
cell
Influenza
37. 2008
• Antigenic shift
• Changes in H and N spikes
• Probably due to genetic recombination between
different strains infecting the same cell
• Antigenic drift
• Mutations in genes encoding H or N spikes
• May involve only 1 amino acid
• Allows virus to avoid mucosal IgA antibodies
Influenza
43. 2008
Pneumocystis Pneumonia
Figure 24.22
• Pneumocystis jiroveci
(P. carinii) found in
healthy human lungs
• Pneumonia occurs in
newly infected infants
& immunosuppressed
individuals
• Treatment:
Timethoprim-
sulfamethoxazole
44. 2008
Pneumocystis
Figure 24.21
The mature cyst contains
8 intracystic bodies.
The cyst
ruptures,
releasing the
bodies.
The bodies
develop into
trophozoites.
1
2
3
The
trophozoites
divide.
4
Each trophozoite
develops into a
mature cyst.
5
Cyst
Intracystic
bodies
Trophozoite
45. 2008
• Blastomyces dermatitidis, dimorphic fungus
• Found in soil
• Can cause extensive tissue destruction
• Treatment: amphotericin B
Blastomycosis
